Directions:
Heat oven to 350°F. Grease a 2 1/2- to 3-quart baking dish. In a
large saucepan over medium-low heat, melt 4 Tablespoons of the butter.
Add the mushrooms and saute, stirring, until mushrooms are browned and
tender. Add the chopped onion and continue cooking for 1 minute. Stir in
the flour until well blended. Gradually stir in the milk. Continue
cooking, stirring constantly, until thickened. Add salt, to taste, and
pepper. Stir in the flaked tuna and peas. Stir in the spaghetti until
well blended. Turn the mixture into the prepared casserole. Sprinkle
Parmesan over the casserole. Melt the remaining 2 Tablespoons of butter
and toss with the bread crumbs. Sprinkle the buttered crumbs over the
Parmesan layer. Bake for 25 to 30 minutes, until lightly browned and
bubbly. Serves 6.